In many medical situations, it is necessary to penetrate the solid or semi-solid biological matter of the human body at substantially precise locations. For example, one common medical practice is placement of a percutaneous endoscopic gastrostomy (PEG) tube.
PEG is a procedure used to put a tube into the stomach of a patient who cannot swallow liquids and solids. FIG. 1A illustrates a PEG tube 112 in place in a human body. In some instances, the tube is instead placed into the small bowel via a gastrostomy. PEG is used in a wide variety of circumstances and generally is effective for helping patients. Traditionally, a PEG tube is placed using endoscopic guidance or x-ray guidance. This step is shown in FIG. 1B. For example, in a traditional PEG procedure to place a PEG tube into a patient's stomach 100, an endoscope is used to observe that the patient's esophagus is without obstruction or diverticulae or for other medical reasons, such as to avoid interference with the pylorus 102. An endoscope is also used to inspect the stomach and inflate the stomach to see that the area selected for the gastrostomy can be distended. In this manner, a medical practitioner (who may be an endoscopist) uses an endoscope to select an area of the lower body of the stomach or antrum (the gastric wall) that is particularly suitable for the PEG tube placement. This step is shown in FIG. 1C.
In another step of the traditional placement of a PEG tube procedure, the endoscopist shines the endoscopic light out from the gastric lumen in a darkened room so that a second medical practitioner (who may be any person trained in such medical procedures) can see the light and identify that it is in a reasonable location of the patient's body, e.g., not above the ribs. FIG. 2 shows how an endoscopic light may be seen to varying degree through the skin of a patient.
FIG. 3 shows another step in the traditional placement of a PEG tube in which the endoscopist will watch the second medical practitioner push a finger into the stomach wall and hopefully see the indentation 104 in the area selected by the endoscopist for the PEG tube placement.
FIG. 4A shows another step in the procedure of placing a PEG tube. If the location of the indentation is suitable, and especially if the indentation is clear, this spot is selected. The assistant then makes a small incision in the skin and inserts a needle 106 into the patient in the area in which the endoscope's light was seen.
FIG. 4B shows another step in the traditional placement of a PEG tube in which the endoscopist will watch a needle 106 as it is pushed through the patient's skin and then through the abdominal wall, and the endoscopist will watch the needle tip enter the stomach in the selected area.
FIG. 5 shows another step in the traditional placement of a PEG tube in which the endoscopist will see a wire 108 pass through the needle 106 into the gastric lumen.
FIG. 6 shows another step in the traditional placement of a PEG tube in which the endoscopist will use an endoscopic snare 110 to grasp the wire 108 firmly. The endoscopist uses the snare 110, passed through the biopsy channel of the endoscope, to firmly grab the wire 108. The endoscope and snare 110 are then withdrawn via the patient's mouth, thereby pulling the wire 108 with it. The part of the wire 108 that extends out from the patient's mouth is subsequently attached to a PEG tube.
FIG. 7 shows another step in the traditional placement of a PEG tube in which the endoscopist has withdrawn the entire endoscope, including the snare 110 holding the wire 108 that was passed through the needle 106, and the wire that passes through the needle extends out of the patient's mouth.
Once the wire 108 is successfully passed through the patient, a PEG tube 112 is secured to the end of the wire extending from the patient's mouth. The PEG tube 112 is guided into the patient's mouth and pulled into the patient's stomach 100 as the wire 108 is pulled from the end that passed through the needle 106. Once the PEG tube 112 is in the stomach, it is pulled partially through the gastric and abdominal walls until the bumper of the PEG tube is snug against the gastric mucosa.
FIG. 8A shows another step in the traditional placement of a PEG tube 112 in which an endoscope is again passed into a patient and subsequently used to visually observe that the bumper of the PEG tube 112 is snug against the gastric mucosa.
In other traditional PEG tube placement procedures, endoscopy is not used at all. Instead, x-ray is used to help select a particularly suitable location in the patient's body (e.g., the stomach) for the introduction of the PEG tube. X-ray is used for guiding the PEG tube placement and for inspecting the PEG tube's final position.